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    M120 Router Major Hardware Components

    Table 1 lists the major M120 router components and characteristics.

    Table 1: M120 Router Major Hardware Components

    Component

    Quantity

    Function

    Redundant

    Field-
    replaceable

    Offline Button

    FEB

    1–6

    Provides route lookup and forwarding functions from FPCs and CFPCs

    Yes

    Yes

    Yes

    Cooling system

    2 front fan trays, 2 rear fan trays (4 fans) Front air filter

    Cools router components

    Yes

    Hot-removable, hot-insertable

    Craft interface

    1

    Displays status and allows you to perform control functions

    Hot-removable, hot-insertable

    FPCs

    1–4

    Connect PICs to other components and houses shared memory

    Hot-removable,
    hot-insertable

    Yes

    CFPC

    1–2

    Combination of a PIC and an FPC; contains the interface circuitry and the FPC as a single assembly

     

    Hot-removable,
    hot-insertable

     

    PICs

    1–4 per FPC

    Provide interfaces to various network media; receive incoming packets from the network and transmit outgoing packets to the network, performing framing and line-speed signaling for their media type; encapsulate outgoing packets received by the FPCs before transmitting them

    Hot-removable,
    hot-insertable

    Yes

    Power supply

    2 AC or 2 DC

    Distributes needed voltages to components

    Yes

    Hot-removable,
    hot-insertable

    Routing Engine

    1–2

    Runs Junos OS ; maintains the routing tables, manages the routing protocols used on the router, controls the router’s interfaces, controls some chassis components, and provides the interface for system management and user access to the router

    Yes

    Hot-pluggable

    Field-replaceable units (FRUs) are router components that can be replaced at the customer site. Replacing FRUs requires minimal router downtime. There are three types of FRUs:

    • Hot-removable and hot-insertable—You can remove and replace the component without powering down the router or interrupting the routing functions.
    • Hot-pluggable—You can remove the component without powering down the router, but routing functions are interrupted until the replacement is installed.
    • Requires router shutdown—You must power down the router before removing the component.

    Published: 2012-08-20